Is It Safe to Use an Immersion Water Heater in a Stainless Steel Cup With Plastic Cover?

I am creating a non-profit product for charity and I have a simple electrical question.

In this product a single cup immersion water heater will go inside a stainless steel cup. So the heater will be touching the metal cup. But I am going to have a plastic safety cover that goes over the metal cup, so someone can not touch the water or metal. 

Does this sound safe enough to sell to the public?  Or is there anything else that might be a problem? 

Thanks so much for any advice. 

ps: I live in Thailand, so it might take me a while to answer any questions, cause of the time difference. 

There are 2 major conductors here, the liquid in the cup, and the metal cup.

All conductor protection, with time, will eventually fail. My suggestion would be to consider a different type of material for the cup and cannot be switched out. Also make a tamper proof switch (something like a circuit interrupter) upon an open circuit for protection.

There are many vulnerabilities and variability's with this idea, it can be done with the proper protection. Porcelain cups would be your best option, but its costly.

Note: Water can heat up to the point of vapor, but plastic will just melt and fail.

I hope this helps.

Good Luck! I hope this works, and is used for what you intend.

Thanks for your reply. It seems with water being involved even with porcelain cups, I have to rely on the user having some care when they use it.

Luck is always helpful

There is a new technology out by Ohmite. They have made a *thick film heater*.

I think it would be perfect for your application, just needs a bit of retrofitting.

You can read about it here, there is an article.

https://issuu.com/eeweb/docs/04-2016_pulse_1_pages